Healthfacts - Calcium channel blockers: three strikes and you’re out?
The antihypertensive drugs known as calcium channel blockers (e.g., Procardia, Cardizem, Adalat, and Calan), already implicated in increasing the risk of heart attack (see HealthFacts, September 1995), are now suspected of causing gastrointestinal bleeding and cancer in elderly people.
Marco Pavor, M.D., Department of Preventive Medicine, University of Tennessee, Memphis, and colleagues followed 750 hypertensive persons, 71 years of age or older, from 1988 to 1992. (American Journal of Hypertension, July 1996). Participants were taking one of the following antihypertensives: a beta-blocker (e.g., Inderal, Tenormin, Lopressor); an angiotensin-converting enzyme (ACE) inhibitor (e.g., Vasotec, Capoten) ; or a CCB. The researchers found that elderly people taking CCBs were twice as likely to develop cancer during the four years compared to those prescribed the other drugs.
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While Dr. Pavor and his colleagues conclude that CCBs may possibly promote cancer, they caution that because of the small number of people followed and the observational nature of the research, a causal relationship between CCBs and cancer is not conclusive. But, they believe the findings suggest the need for further clinical trials. In an accompanying article, cancer researcher Janet R. Daling, Ph.D, Fred Hutchinson Cancer Research Center, Seattle, outlines why an association between CCBs and cancer is biologically plausible and also encourages further study.
In another study published this year, Pavor and colleagues followed 1636 hypertensive persons who were 68 or older from 1985 through 1992 and who were taking beta-blockers, ACE inhibitors or CCBs. (Lancet, 20 April 1996) CCBs were found to increase the risk of gastrointestinal bleeding by almost 50% compared to either of the other two drugs.
The researchers conclude that choice of an antihypertensive drug should be based on the available evidence on long-term safety and benefit. Pavor and colleagues urge doctors to use prudence in prescribing CCBs for elderly people, especially those with a history of gastrointestinal bleeding or those at high risk for gastrointestinal bleeding, such as regular high-dose users of aspirin.
In an editorial accompanying the CCB and Cancer study, Michael J. Alderman, M.D., Albert Einstein College of Medicine, points out that concern about CCB risk derives from studies like these in which patients took short acting versions. Since the early 1990s long acting versions (e.g., Procardia XL, Cardizem CD) have been heavily promoted to doctors and consumers. While noting that some experts believe that the long acting CCBs are safer, Dr. Alderman cautions that this opinion … is based on hope (or hype) and not evidence. He recommends Diuretics and beta-blockers first — others when necessary or specifically indicated.
CCBs have a role in treating a minority of people with hypertension, for example, those whose blood pressure is unresponsive to diuretics and beta-blockers. But CCBs have been heavily promoted to doctors by their manufacturers and, consequently, are overprescribed. Most are still under patent, which makes them far more expensive than the diuretics and beta-blockers. And most importantly, two older drug classes have been proven in clinical trials to reduce the risk of stroke and heart attack, but the CCBs have not.
COPYRIGHT 1996 Center for Medical Consumers, Inc.
COPYRIGHT 2004 Gale Group
